A pilot development of virtual stimuli depicting affective dispositions for penile plethysmography assessment of sex offenders

There are concerns regarding the reliability, realism, and validity of stimulus materials used in the assessment of sexual interests among sex offenders. This article explores new stimulus materials for use with penile plethysmography (PPG) assessments. First, this paper presents a pilot study where undergraduate students rated virtual characters (male and female) on perceived age. In addition, the materials developed are unique in that they depict the characters exhibiting varying affective dispositions, including neutral, fearful, sad, joyful, and seductive. Participants in the first study were also asked to identify the affective disposition of the virtual characters, and results suggest that affective disposition was largely perceived as intended, especially in terms of identifying the general emotional valence of the affective dispositions (i.e., positive versus negative). In a second pilot study, we used the computer-generated images to measure sexual arousal responses in a group of non-deviant males recruited in the community. Responses measured through penile plethysmography suggest participants responded to the stimuli as expected, as the greatest amount of sexual arousal was recorded when participants were shown the adult female character. In addition, participants responded with significant arousal only when the adult female character was depicted as sexually open (joyful or seductive), rather than sexually closed or neutral. Results suggest these materials may discriminate sexual interests if applied within clinical forensic assessment of sex offenders.